IR Demo Project Weekly Report
April 19-23, 1999
Highlights of the week include installing a new cathode wafer, vacuum-baking the gun, and getting ready for the FEL Program Closeout scheduled for Monday and Tuesday of next week.
Hermann Grunder escorted Richard Seaman, an analyst for the Virginia Commonwealth House Appropriations Committee, on a tour of the FEL this week. In addition, Linda Johnson and Mark Moran from NAWC visited this week to discuss optical coating development in support of the IR FEL Upgrade.
FEL Installation/Maintenance Activities
The autocorrelator hardware was repaired and checked using the diagnostics software and a few minor maintenance tasks were completed.
The machine is ready to go and awaiting restoration of the electron gun.
FEL Commissioning Activities
A new cathode wafer was installed and the gun was vacuum baked. It will cool down over the weekend and the bake will be disassembled Monday.
High-voltage processing will proceed after that. We project turning on electron beam either Wednesday or Thursday of next week, depending on how rapidly the HV processing progresses.
RF calibration of the cryounit cavities was rechecked; essentially the same results were obtained as in the past. The measurements are difficult to do to better than ~15% accuracy because they are very sensitive to the waveguide coupling to the cavities (specifically, the external Q) which, in turn, is difficult to establish accurately.
Additional planning of CSR experiments and supporting simulations was done as partial preparation for the upcoming May run. The top-level focus will be determining whether the emittance grows in the first recirculation arc and, if so, whether CSR is the predominant influence on the growth. Scans of emittance versus cryomodule gang phase taken during March do indeed reflect a general emittance growth, but we need to check the reproducibility of the scans and understand the root causes of their features in detail.